This invention involves a shellfish dredge and more particularly a bivalve mollusk harvesting apparatus used on a dredge.
In my U.S. Pat. No. 4,425,723 which issued Jan. 17, 1984, a dredge for harvesting clams, quahogs, and the like, is described with at least two cross bars connecting the skids together. Tines are attached to the cross bars angled downwardly forming at least two parallel rows. One of the apparatuses described in my patent utilizes reduced spaces between the tines from the front to the back of the apparatus. While this apparatus certainly works satisfactorily, it has been determined that certain configurations under my patent do not harvest the clams in the most efficient fashion. A tendency has been observed that there is a high drag in pulling the device and there is not a sufficiently efficient flow of material through the apparatus. In my prior apparatus, the sand from the bottom is picked up with the mollusks and there is a flow of almost liquid character up the tines and to the rear of the sled. That flow is a solid mass of mollusks and sand, with mostly sand being picked up at the front of the sled. On the sides of the sled, it is necessary to affix screens that prevent the mollusks from falling off the side of the sled once picked up. The flow described above tends at higher speeds of drag not to dissipate the sand before it reaches the rear of the skid. Further the prior device does not sufficiently sort the mollusks as to size. U.S. Pat. No. 3,226,854 to Mero describes a dredge underwater pick up head assembly which utilizes a vacuum pipe line to pick up small sized objects, a "U" shaped head assembly with the entire center section of tines positioned flat toward the movement direction is utilized with a screen to prevent large object from entering into the vacuum pipe line. This configuration is opposite to the performance required for the effective collection of the larger mollusks. This type of suction apparatus typically destroys a major portion of the clams and fills them with sand which in part is never removable. This type of apparatus does not satisfy the needs above nor attain the objects described hereinbelow.